fix(core): added @angular/compiler as a peer dependency (#55610)

This fixes an issue with packages managers likes pmpm
that will not link the @angular/compiler package to the @angular/core
package if it is not listed as a peer dependency.
I added it as optional peer dependency as it's only used in special cases.

Fixes #38096

PR Close #55610

packages/core/package.json

@@ -19,9 +19,15 @@
     "tslib": "^2.3.0"
   },
   "peerDependencies": {
+    "@angular/compiler": "0.0.0-PLACEHOLDER",
     "rxjs": "^6.5.3 || ^7.4.0",
     "zone.js": "~0.15.0"
   },
+  "peerDependenciesMeta": {
+    "@angular/compiler": {
+      "optional": true
+    }
+  },
   "repository": {
     "type": "git",
     "url": "https://github.com/angular/angular.git",